I did the same thing with mine and 3D printed covers in ASA-CF. Made some changes to mine with a TPU gasket at the recommendation of purdyd that seems to have worked really well. I also added LockTight to the screws as they kept loosening from driving over time.
Actually, your design and idea to 3D print a cover was what got me to start designing a cover for mine.
I ended up doing the first few in PLA-CF to get that added strength to combat warping, but then switched to ASA-CF (for the outdoor resiliency and strength), set infill to 100%, built up the...
I ended up putting a few larger washers on the bottom side to give that added pressure to seal it. But I also like the idea of having a solid single piece to apply the pressure from the inside. That might make it for Rev. 6 of this.
I was going to do a TPU gasket and then inset it into the...
Finally got around to installing the digital twin tailgate seal. Had to make some minor modifications to it to accommodate the bed cover rails, but it works great.
I also spent the past week trying to 3D scan, model, and print covers for the Stake pockets to help prevent water leakage...